If I have learned anything, it's that you can't assume anything with holidays and family. DH has an aunt who has brought the same thing to every single Thanksgiving and Christmas meal for the last ten years - yummy yeast rolls that she buys from a coworker, whose church makes the rolls en masse as a fundraiser. I hosted Christmas for the first time ever a few years ago* and I don't think aunt was very happy about it.
When I called her to officially issue the invite and talk about what everybody was bringing, I said, "I'm going to assume that you're bringing the yeast rolls as usual?"
Aunt huffed and said, "NO, why would I bring yeast rolls?"
I said, "OK, then, bring whatever side that makes you comfortable." and hung up.
*I haven't hosted a holiday since, not because it went badly, but because the following year we gave DH's sister the cut direct. We didn't want her in our home, but we didn't want to make it impossible for her to attend holidays. That seemed cruel. (We would schedule our arrival around her leaving.)